Draw a rectangle for the wall outline
Add horizontal guide lines for the brick rows
Offset every other row so the joints are staggered
Draw vertical lines to separate individual bricks
Vary brick sizes slightly for a natural look
Round or roughen some edges if desired
Add thin mortar gaps between bricks
Darken the outer outline and key brick edges
Shade one side of each brick for depth
Add texture with small cracks, chips, or speckles
Erase guide lines and clean up the drawing